Hollow door frames formed of a metal material such as aluminum, screen doors for example, are comprised of parallel top and bottom rails and parallel vertical side rails. It is common practice to join the mitered corners of the various rails with angle gussets, however, various forces created by the stresses and strains imposed on the door from its own weight as well as by hard usage often bend or twist the angle gussets, resulting in the opening of one or more of the corner miter joints.
While the corner gusset of the present invention is particularly adapted for use in the construction of screen doors, it is equally adaptable for use in forming rigid miter corner connection in other types of doors as well as windows, and other articles formed of sheet metal members, etc.